The New York Times has published an article on personal fabrication entitled "Beam it from the Web" (free registration required), which looks at the state of the technology and the efforts of some companies to bring it to the home. But the reason I call it to your attention is the concluding sentence. One of the experts consulted, Professor Hod Lipson of Cornell, ends on this note: “A milestone for us would be to print a robot that would get up and walk out of the printer... batteries included.”